Both federal and local government offices are likely to have an even better grasp of your family's history than you do, by way of copious, meticulous records. The U.S. Census is an invaluable starting point for amateur genealogists. Although the original 1790 census was little more than a population count, it eventually grew into a much more detailed inquiry, yielding a lot of very helpful data to the country then, and to genealogy buffs now. Topics have expanded each decade from the most basic information to include items like home ownership and immigration status. In 2014, the most recent results available to the public are from the 1940 census because they're released 72 years after the fact [source: 248 Ancestors]. (Note: The actual census records are housed at the National Archives).
On a local level, county and city courthouses often are home to valuable tax, birth, death, property, marriage and criminal records, provided you know where to look. Military records also can shed light on family history and migration patterns, and can be accessed thanks to sites like Fold3, which features service data as far back as the Revolutionary War.